This invention relates to surgical fastener applying apparatus, and more particularly to surgical fastener applying apparatus in which the tissue to be fastened is first clamped in the apparatus and then fastened by application of the fasteners.
Various devices have been developed for applying surgical fasteners in lieu of conventional sutures. Some of these devices apply metal staples; others apply two-part fasteners of resinous materials. The term "surgical fasteners" is used herein as a generic term for all such fasteners.
Many surgical fastener applying devices, especially those intended for fastening internal body tissue, are designed to clamp the tissue before applying the surgical fasteners to it. The known devices of this kind take several forms. Hirsch et al. U.S. Pat. No. 3,275,211 shows a device in which a surgical staple holding assembly reciprocates linearly relative to an anvil in response to rotation of a control knob. After tissue has been clamped between the anvil and the staple holding assembly, a plurality of metal surgical staples are driven simultaneously by operation of a pivoting handle.
Green U.S. Pat. Nos. 4,354,628 and 4,383,634 show other devices which accomplish a similar result in a different way. In the Green devices, the staple holding assemblies are pivotally mounted relative to the anvil (although limited relative linear translation of these elements may also be possible in these devices). Pivoting levers are used to pivot the staple holding assembly toward the anvil in order to clamp the tissue between these elements. After the tissue has been clamped, a pivoting handle is operated to simultaneously drive a plurality of metal staples through the tissue.
Green U.S. Pat. No. 4,383,634 (FIG. 14) shows that the use of levers to control the tissue clamping function is not limited to devices in which the fastener holding assembly and the anvil are pivotally related. This principle can also be applied to devices in which the fastener holding assembly translates linearly relative to the anvil as in the Hirsch et al. device.
Devices of the type shown by Hirsch et al., in which a knob is used for controlling the position of the staple holding assembly, have the characteristic that the spacing between the staple holding assembly and the anvil is adjustable by the operator. On the other hand, operation of devices of the type shown by Green, in which levers are used to close the device on the tissue, may be faster.
Because the spacing between the staple holding assembly and the anvil in devices of the type shown by Green is not adjustable, it is generally not possible to adjust the location of the apparatus relative to the tissue after the tissue has been clamped. Of course, it is usually possible to reopen the instrument and reposition it if the original position is not satisfactory. But it would be desirable to have the ability to adjust the position of the apparatus relative to the tissue without having to completely reopen the instrument.
It is therefore an object of this invention to improve surgical fastener applying apparatus of the type in which levers are used to operate the elements which clamp the tissue prior to application of the surgical fasteners.
It is a more particular object of this invention to provide surgical fastener applying apparatus having levers for operating the elements which clamp the tissue prior to fastening and having an intermediate latching position in which the instrument is partly closed on the tissue but the tissue is not clamped so that the position of the instrument relative to the tissue can be adjusted without reopening the instrument.